The present invention relates to new compositions composed of hydrogen-containing fluorochlorohydrocarbons and acetone. The fluorochlorohydrocarbons are selected from the group consisting of dichloropentafluoropropanes. It further relates to the use of these compositions for cleaning surfaces of objects or for fixing toner which is applied to a recording carrier in the fixing apparatus of printers and copiers.
Very high demands are placed on solvents for cleaning purposes and for fixing toner. Such solvents should have a relatively low boiling point, should be non-flammable and largely non-toxic, and should have beneficial solvent properties for impurities which are to be removed or for toner particles which are applied to a recording material and are to be fixed by solubilizing. However, these demands, as a rule, cannot be met by only one single pure solvent. Therefore, in practice, a large number of solvent mixtures with differing compositions are used. For instance, it is generally known to use mixtures of fluorochlorohydrocarbons (as the main solvent) with a co-solvent for industrial cleaning processes or for vapor degreasing in addition to pure chlorinated and/or fluorinated hydrocarbons. Such mixtures may be either nonazeotropic, azeotropic or azeotrope-like. "Azeotrope-like" is understood to mean that mixtures boil substantially constantly over a relatively large concentration range (change in boiling temperature of not more than 5.degree. C.) and, therefore, behave similarly to azeotropes for practical use. Solvent mixtures which when boiling contain in the vapor phase the solvent constituents of the mixture in the same relative composition as in the liquid phase are regarded as azeotropes. Solvent mixtures which are suitable for use in fixing apparatus of printers and copiers generally consist of at least two solvent constituents, at least one of which has toner-solubilizing properties. Since solvent mixtures in modern fixing apparatus act on the toner in the vapor state, the solvent mixture should evaporate as evenly as possible, i.e. without separating into the constituents or at least without relatively large shifts in the proportions of the constituents, in order to ensure continuous fixing of the toner on the recording material even over relatively long periods of use. For this purpose, the preferred solvent mixture used in the fixing apparatus has azeotrope-like, but most preferably azeotropic, boiling properties. However, it is not possible to predict the formation of azeotropic or azeotrope-like compositions, which renders the search for new azeotropic or azeotrope-like solvent systems more difficult.
Although many attempts have already been made to obtain compositions with the desired properties for different fields of use, the known mixtures are still inadequate because they either are unsuitable for certain purposes, are toxic or adversely affect the environment. For instance, in conjunction with the further technical developments in the field of fluxes, new demands have arisen relating to the removal of the newly developed fluxes. Known solvent mixtures are frequently unsatisfactorily for this purpose. Furthermore, known solvent mixtures are often multi-component systems of complicated composition or contain relatively large proportions of solvents which are toxic or have low flash points, and are, therefore, unsafe. For a range of solvent constituents, further replacement by other solvents which are at least equally well suited for the respective purposes is desirable from an environmental standpoint.